Process for making terminal banks.



UNITED STATES PATENT OFFICE.

AMOS F. DIXON, OF NEWARK, NEW JERSEY, ASSIGNOR '10 WESTERN ELECTRICCOMPANY, OF NEW YORK, N. Y., A CORPORATION OF ILLINOIS.

PROCESS FOR MAKING TERMINAL BANKS.

Specification of Letters Patent.

Application filed February 26, 1912. Serial No. 679,945.

To all whom it may concern:

Be it'known that I, Amos F. DrxoN, citi-' zen of the United States,residing at Newark, in the county of Essex and State of New Jersey, haveinvented a certain new and useful Improvement in Processes for MakingTerminal Banks, of which the following is a full, clear, concise, andexact description.

This invention concerns selector switches such as are used in automatictelephone exchanges, and has to do particularly with the process ofmaking the terminal boards thereof, that is, the boards which carry themultipled line terminals.

In constructing terminal boards composed of alternate layers ofsheet-metal and insulation, great difliculty is encountered due to-thevariations 1n thickness of the insulating sheets and of the sheets ofmetal. Since these variations are cumulative, 1t

.becomes impossible to stack up any considerable number, one above theother, so

that the centers between terminals and consequently also the overalldimension will be at all uniform. It can be readily appreciated that ifthe rubber or mica or other insulating material should vary even, say,half a thousandth of an inch, by the way a small commercial variation,the cumulative variation on such a mass of terminals as used on anordinary board would be'very great and make successful construction wellnigh impossible. The present invention overcomes this difiiculty andenables the production of a cheap and efficient terminal board.

Considered broadly, the invention consists in the process of superposingsheets of flexible insulating material, such as paper, coated .with aplastic insulating compound, and sheets of terminal forming metal, andapplying pressure to the resulting structure until the. overalldimensions are reduced to the desired amount. It is a peculiarity ofthis process that, in the finished product so formed, not only may theoverall dimen sions, be regulated with extreme nicety, but

- the distance between the individual strips is equally and uniformlyreduced to the required figure. I may use a compound which is originallysufiiciently plastic for the purpose, but which dries and hardens whenexheat and which hardens sufiiciently to maintain rigid the terminalsheets when allowed to cool. It is desirable that the compound benon-hygroscopic and have first-class insulating qualities; also thatthese qualities be stable. I

In the drawings, Figure, l is a front elevation of a portion of thecompleted terminal bank; and Fig. 2 is a perspective view of thesuperposed sheets during the process of assembly.

Referring to the drawings, 10 designates a punchingof sheet metalpreferably having ears or lugs adapted to form the contact terminals t25 The cars upon each metallic strip form multiple terminals of the sameline on both faces of the board, so that each line is accessible toevery brush on both sides of the board. A line may have but a singleterminal t or may consist of what are known in telephony as the tip,ring and sleeve terminals, 27, 25 t. Attention is called to the peculiarformation of the .a manufacturing stlindpoint, wire may be substitutedfor the sheet metal. The sheets of metal after being punched into shapeare stacked up alternately with paper coated with an insulating compoundwhich is or mav be caused to become plastic.

Paper, as is well known is one of the few substances which can bemanufactured in sheets which vary but little in thickness. It is alsoafirst-class insulator. Therefore I prefer to use paper as a base forthe insulating compound.

A very desirable compound may be made from elaterite fused with linseedoil, but it is of course understood that any equivalent compound may beused without de arting from the scope of the invention. The resultantinsulating elements consisting of the paper sheet and its compound arethen stacked up alternately until the desired number of terminals isobtained. A convenient method of doing this is shown in Fig- 2andconsists in perforating the metal sheets 10 and insulating elements11 and threading themupon sleeves 12, 12' of insuioo - the requirednumber has 4 top plate 18 is secured in place. As many v is removed, thenuts 'lation slipped over the rods 13, 13 secured at their lower ends tothe base 18, and when been built up, the

bolts 13 and their sleeves are provided as may be necessary. Theresultant structure is then placed between heavy iron clamps, (notshown) and heated so that the insulating compound becomes somewhatviscous,

and pressure is applied by means of the amount of compression to insurethe proper overall dimensions and consequently the proper distancebetween individual sheets. They are provided with 111115921, 21ai1d 16,16 respectively; The heating process may thenbe" discontinued; Thecompound there; upon hardens and the is then removed 1 sheets coatedwith from the clamps a solid, homogeneous mass" having uniformly-spaced,projecting lugs. 4

I claim z 1. The process of makin terminal boards consisting ofsuperposing exible insulating sheets coated with a plastic insulatingcompound and metal strips, and subjecting the structure thus built up topressure.

2. The process of making terminal boards consisting in superposingflexible insulating pound and metal having projecting lugs, andsubjecting the structure thus built up to pressure.

a plastic insulating com- 3. The process of making terminal boardsconsisting in superposing in alternate layers, sheets of paper coatedwith a plastic insulatcompound and sheets of metal having projectinglugs, subjecting the structure thus built up to pressure in the presenceof heat to uniformly space the terminal sheets, and finally allowingsame to cool.

In witness whereof, I, hereunto subscribe my name this 24th day of Feb.A. D., 1912.

AMOS F. DIXON. Witnesses:

- IRVIiIG MAc-Do unn,

WAL ER F. HOEEMAN.

